Field
The present disclosure relates to techniques for completing a reservoir. More particularly, the present disclosure relates to tools and methods for intelligent completions and monitoring systems.
Description of the Related Art
Exploring, drilling and completing hydrocarbon wells are generally complicated, time consuming and ultimately very expensive endeavors. Thus, maximizing recovery is a significant concern in any well operation. Along these lines, over the years, wells have tended to become deeper and deeper, perhaps exceeding 30,000 feet in depth, and of fairly sophisticated architecture to help ensure greater access to the reservoir. Similarly, increased attention has also been paid to monitoring and maintaining the health of such wells. A premium is also placed on maximizing the recovery rate and extending the overall life of the well as much as possible.
Of course, maximizing recovery, the recovery rate and the overall life of the well are dependent on a host of different factors, not the least of which is the condition of the well architecture. For example, most of the well may be defined by a smooth steel casing that is configured for the rapid up hole transfer of hydrocarbons and other fluids from a formation. However, a buildup of irregular occlusive scale, sludge, wax and other debris or “asphaltenes” may occur over time at the inner surface of the casing or tubing and other architecture so as to restrict flow. Such debris may even form over perforations in the casing, screen, or slotted pipe thereby also hampering hydrocarbon flow into the main borehole of the well from the surrounding formation.
In many cases this buildup is a function of pressure. For example, sudden pressure drops at downhole locations near restrictions may be prone to develop asphaltene buildup. Of course, removing such restrictions to avoid buildup and enhance recovery would only compromise the architecture of the well and hamper recovery in a different manner. Further, this would not eliminate all buildup given that even asphaltene may continue to buildup in absence of such restrictions.
As a practical matter, instead of altering well architecture, buildup as described above is dealt with by first detecting the buildup and then performing an interventional application to achieve its removal. For example, over the course of the life of the well logging applications may be run to detect and map out downhole well conditions. This includes running a logging tool through the well to attain and record such conditions, including locations of potential buildup. Once detected, a variety of cleanout techniques may be utilized to remove debris from the well so as to help ensure unobstructed hydrocarbon recovery.
Unfortunately, performing a complete cleanout generally requires shutting down production and proceeding with another intervention. For example, once asphaltene buildup is detected, production is often shut down, followed by the introduction of a solvent such as xylene that fills the well for a couple of days and is then pumped out. This is then followed by re-examining the well condition and resuming production if the buildup has been sufficiently removed by the solvent-based cleanout.
Of course, the interventional cleanout is an expensive undertaking. In fact, even setting aside the equipment, operator and material cost of a cleanout as described above, there is also the expense of shutting down production for days at a time. All in all, restoring the architecture of the well to an optimum buildup-free state may cost the operator several hundred thousand if not a million or more in today's dollars.
Efforts have been undertaken to try and avoid the need for such costly cleanouts. These efforts may focus on preventing buildup and thereby avoiding the need for such an all-encompassing interventional cleanout. For example, to avoid asphaltene buildup in particular, modeling of the well may take place to help estimate a flow rate threshold to stay under and reduce the likelihood of asphaltene deposits. This manner of avoiding sudden pressure drops may be effective, however, it also compromises the ability of the well to produce at a maximum rate. Once more, this technique is employed in a blind fashion. That is, the rate of production is compromised without any direct indication of problematic buildup actually starting to develop.
Similarly, a circulating chemical injection system may be incorporated into the well hardware and employed to deliver a metered amount of chemical mixture on a near continuous basis to help prevent such buildup. However, this requires an added hardware and material expense along with the expense of separating the chemical mixture from production once the well fluids are produced. Further, this again takes place in a largely blind fashion, adding on these expenses without any direct indication of problematic buildup actually starting to develop.